let D be non empty set ; for f being FinSequence of D
for k2 being Nat st 1 <= k2 & k2 < len f holds
f = (mid (f,1,k2)) ^ (mid (f,(k2 + 1),(len f)))
let f be FinSequence of D; for k2 being Nat st 1 <= k2 & k2 < len f holds
f = (mid (f,1,k2)) ^ (mid (f,(k2 + 1),(len f)))
let k2 be Nat; ( 1 <= k2 & k2 < len f implies f = (mid (f,1,k2)) ^ (mid (f,(k2 + 1),(len f))) )
assume A1:
( 1 <= k2 & k2 < len f )
; f = (mid (f,1,k2)) ^ (mid (f,(k2 + 1),(len f)))
then
mid (f,1,(len f)) = (mid (f,1,k2)) ^ (mid (f,(k2 + 1),(len f)))
by INTEGRA2:4;
hence
f = (mid (f,1,k2)) ^ (mid (f,(k2 + 1),(len f)))
by A1, FINSEQ_6:120, XXREAL_0:2; verum